The present invention relates to a liquid crystal flat panel display. More particularly, in one embodiment, the flat panel display of the present invention has layers of Indium Tin Oxide (ITO), or other optically transparent electrically conductive materials, coated on the front and rear external glass surfaces under the front and rear polarizers. The ITO layer at the front of the display acts as an electromagnetic interference (EMI) filter or shield. The ITO layer at the back of the display is used as a heater. Each ITO layer may or may not be overcoated on one or both sides with index matching dielectrics to improve optical transmission through the ITO coatings, and/or reduce the optical reflections at the front and/or rear surfaces of the ITO layers.
In an alternative embodiment, the ITO heater layer is placed on the inside surface of the rear glass plate allowing the ITO heater layer to be closer to the liquid crystal layer. This reduces the thermal resistance between the ITO layer and the liquid crystal layer thus reducing the amount of power necessary to heat the liquid crystal layer. In the preferred embodiment, bus bars are placed along predetermined edges of the ITO heater layer. The bus bars allow for the uniform injection of current into the ITO heater layer. It is also preferred that thermal sensors be placed on the inside portion of the glass and in close proximity to the ITO layer to detect the heat being inputted into the liquid crystal layer.
In another alternative embodiment, an integral metal heater is used instead of the ITO heater layer. The metal heater is applied to the TFT layer and is in close proximity to the liquid crystal layer to provide improved and efficient heating capabilities.
In another alternate embodiment, a black mask EMI layer is interposed between the front and back glass plates. In the preferred embodiment, the EMI layer is isolated from Vcom and tied to zero potential. It is preferred that the integral metal heater be placed behind the black mask EMI layer so that no portion of the heater is visible and no portion of the heater interferes with the pixel apertures.
In another alternate embodiment, integral thermal sensors may also be layered onto the TFT array layer preferably under the black mask EMI layer. In this embodiment, thermal resistivity between the integral heater and the thermal sensor(s) is reduced leading to faster thermal sensor response times. It is appreciated, as discussed in further detail below, that features of the alternate embodiments discussed above may be combined to form additional alternative flat panel display designs. For example, a flat panel display may be configured with all of the inventions of the isolated black mask EMI layer, integral thermal sensor and integral heater combined in one flat panel display.
In addition to the features mentioned above, objects and advantages of the present invention will be readily apparent upon a reading of the following description.